Devices and methods for the minimally invasive treatment of spinal stenosis

ABSTRACT

Multiple implants and methods for the minimally invasive treatment of spinal stenosis are disclosed. A spinal implant device includes a spacer region and an attachment region. The spacer region is adapted to be positioned between first and second spinous processes of first and second vertebral bodies to limit movement of the first spinous process and the second spinous process toward one another. The attachment region attaches to the first spinous process via a fastener that extends substantially along a long axis of the spinous process.

REFERENCE TO PRIORITY DOCUMENTS

This application is a continuation of and claims priority to co-pending U.S. patent application Ser. No. 11/881,584 issuing as U.S. Pat. No. 8,303,630 on Nov. 6, 2012, which is incorporated herein by reference in its entirety, and which claims priority of the following co-pending U.S. Provisional Patent Applications: (1) U.S. Provisional Patent Application Ser. No. 60/834,209, filed Jul. 27, 2006; (2) U.S. Provisional Patent Application Ser. No. 60/834,003, filed Jul. 28, 2006; (3) U.S. Provisional Patent Application Ser. No. 60/860,942, filed Nov. 24, 2006. Priority of the aforementioned filing dates is hereby claimed. The disclosures of the Non-provisional and Provisional Patent Applications are hereby incorporated by reference in their entirety.

BACKGROUND

The present disclosure is related to orthopedic devices implanted between skeletal segments. The implanted devices are used to adjust and maintain the spatial relationship(s) of adjacent bones. Depending on the implant design, the motion between the skeletal segments may be returned to normal, increased, modified, limited or completely immobilized.

Progressive constriction of the central canal within the spinal column is a predictable consequence of aging. As the spinal canal narrows, the nerve elements that reside within it become progressively more crowded. Eventually, the canal dimensions become sufficiently small so as to significantly compress the nerve elements and produce pain, weakness, sensory changes, clumsiness and other manifestation of nervous system dysfunction.

Constriction of the canal within the lumbar spine is termed lumbar stenosis. This condition is very common in the elderly and causes a significant proportion of the low back pain, lower extremity pain, lower extremity weakness, limitation of mobility and the high disability rates that afflict this age group.

The traditional treatment for this condition has been laminectomy, which is the surgical removal of the lamina portion of bone and the adjacent ligamentous structures that constrict the spinal canal. Despite advances in surgical technique, spinal decompression surgery can be an extensive operation with risks of complication from the actual surgical procedure and the general anesthetic that is required to perform it. Since many of these elderly patients are in frail health, the risk of developing significant peri-operative medical problems remains high. In addition, the surgical resection of spinal structures may relieve the neural compression but lead to spinal instability in a substantial minority of patients. That is, removal of the spinal elements that compress the nerves may weaken the vertebral column and lead to spinal instability and vertebral mal-alignment. With instability, the vertebrae will move in an abnormal fashion relative to one another and produce pain, nerve re-impingement, weakness and disability. Further, re-stabilization of the spinal column requires additional and even more extensive surgery. Because of these issues, elderly patients with lumbar stenosis must often choose between living the remaining years in significant pain or enduring the potential life-threatening complications of open spinal decompression surgery.

Recently, lumbar stenosis has been treated by the distraction—instead of resection—of those tissues that compress the spinal canal. In this approach, an implantable device is placed between the spinous processes of the vertebral bodies at the stenotic level in order to limit the extent of bone contact during spinal extension. Since encroachment upon the nerve elements occurs most commonly and severely in extension, this treatment strategy produces an effective increase in the size of the spinal canal by limiting the amount of spinal extension. In effect, the distraction of the spinous processes changes the local bony anatomy and decompress the nerves at the distracted level by placing the spinal segment into slight flexion.

Unfortunately, the placement of a conventional inter-spinous implant requires surgical exposure of the posterior and lateral aspects of the spinous processes as well as the posterior aspect of the spinal column. Since these operations still carry a significant risk of peri-operative complications in the elderly, there remains a need in the field for devices and methods that reduce the scope of the surgical procedure and its inherent risks.

SUMMARY

This application discloses a series of novel devices and methods for the minimally invasive treatment of spinal stenosis. In an embodiment, distraction members are percutaneously placed into the space between two adjacent spinous processes. The distraction members are attached to a distraction platform and the platform is configured to adjustably distract and set the distance between the distraction members. With actuation of the distraction platform, the outer surfaces of the distraction members forcibly abut the spinous processes and distract the adjacent spinous processes away from one another. The inner surface of at least one distraction members forms a guide channel that is adapted to guide and position an orthopedic implant into the distracted interspinous space. The implant is adapted to maintain the increased distance between the spinous processes after removal of the distraction members and distraction platform.

In an alternative embodiment, distraction members are percutaneously placed into the tissues adjacent to the spinous processes and used to introduce an implant delivery device. The implant is attached to and contained within the delivery device. With actuation, the implant is rotated into the inter-spinous space and used to forcibly separate the spinous processes.

In another embodiment, a pin or similar anchor is placed at least partially through a first spinous process and positioned so that the distal end abuts a surface of an adjacent spinous process. The pin is used to separate the two adjacent spinous processes and maintain the increased distance between them. In another embodiment, a pin is placed into the base of the superior facet of the lower vertebra and used to limit vertebral extension by preventing the downward travel of the inferior facet of the superior vertebra. Preferably, the pin has a hollow central cavity that accommodates a bone graft or a bone graft substitute and is adapted to fuse with the surrounding bone at the insertion site of the inferior vertebra. Additional embodiments are disclosed that modify the facet joint anatomy and provide direct nerve decompression and/or a limit of vertebral extension.

In another embodiment, an implant is attached onto at least one vertebral bone and adapted to limit the motion of the attached bone relative to an adjacent vertebra. The motion pathway permitted by the implanted is substantially curvilinear and has at least one center of rotation near the natural Instantaneous Axis of Rotation between adjacent vertebrae. Further, the implant permits greater relative motion between the adjacent vertebrae in flexion than it does in extension.

In one aspect, there is disclosed an orthopedic device, comprising a first member adapted to be attached onto at least one vertebra arid adapted to limit the motion of the attached vertebra relative to an adjacent vertebra, wherein the first member defines a motion pathway of the attached vertebra, wherein the motion pathway is substantially curvilinear and has at least one center of rotation near a natural instantaneous axis of rotation between the attached vertebra and the adjacent vertebrae and, wherein the first member provides limited relative motion between two vertebrae such that the relative motion is greater in flexion than it is in extension.

In another aspect, there is disclosed a method for the treatment of spinal stenosis in which an orthopedic implant is introduced into a space between the spinous processes of two adjacent vertebras using a minimally invasive surgical technique, comprising: placing two extension members into the space between two adjacent spinous processes of adjacent vertebrae, wherein the extension members are coupled to a distraction platform device capable of adjusting a distance between the extension members; using the distraction platform to separate the extension members, wherein the outer surface of each extension member is adapted to abut a spinous process of each adjacent vertebra so that separation of the extension members by the platform produces an increase in the distance between the adjacent spinous processes, wherein an inner surface of at least one extension members forms a guide channel that is adapted to guide and position an orthopedic implant into the distracted inter-spinous space; placing an orthopedic implant into the space between the two adjacent spinous processes, wherein the implant is adapted to maintain the increase in distance between the adjacent spinous processes after removal of the extension members; and removing the extension members and the distraction platform.

In another aspect, there is disclosed a method for the treatment of spinal stenosis in which an orthopedic implant is introduced into the space between the spinous processes of two adjacent vertebrae using a minimally invasive surgical technique, comprising: positioning two extension members adjacent to, but not into, an inter-spinous space between two adjacent spinous processes, wherein the extension members are coupled to a distraction platform device capable of setting a distance between the extension members; using the distraction platform to separate the extension members, wherein the outer surface of each extension member is adapted to separate tissue adjacent to the inter-spinous space, wherein an inner surface of at least one of the extension members forms a guide channel that is adapted to guide and position an implant delivery device into the tissue adjacent to the inter-spinous space, wherein the implant is adapted to be attached onto the delivery device and be at least partially contained therein, wherein the implant delivery device is adapted to rotate the attached implant about a center point that is substantially contained within the delivery device and through an angle range of 45 to 135 degrees; deploying the implant delivery device onto the extension members, wherein the implant delivery device has an attached orthopedic implant; placing the attached orthopedic implant into the space between the two adjacent spinous processes, wherein the implant is adapted to maintain a distance between the spinous processes after removal of the extension members; and removing the delivery device, extension members and the distraction platform.

In another aspect, there is disclosed a method for the treatment of spinal stenosis, comprising: placing a body of a pin at least partially through a first spinous process such that one end of the pin is positioned to abut a surface of a second, adjacent spinous process that faces the first spinous process; and using the pin to set and maintain a distracted space between the spinous processes.

In yet another aspect, an orthopedic device is disclosed. In one embodiment, the device comprises a first member configured to attach onto at least one first vertebra and limit motion of the first vertebra relative to a second, adjacent vertebra. The first member defines a substantially curvilinear motion pathway of the first vertebra having at least one center of rotation near a natural instantaneous axis of rotation between the first vertebra and the second vertebra. The first member is configured to provide limited relative motion between the first vertebra and the second vertebra such that the relative motion is greater in flexion than it is in extension.

In another aspect, an assembly for placement or an orthopedic implant within a target inter-spinous space of a spinal column is disclosed. In one embodiment, the assembly comprises: (i) an implant placement device comprising: at least a first extension member and a second extension member each of the first and second extension members comprising an elongated segment configured to extend from a proximal aspect to a distal aspect and each of the first and second extension members configured to be positioned within the target inter-spinous space at the distal aspect thereof, and a distraction mechanism configured to connect to the proximal aspect of each of the first and the second extension members, and to forcibly move the first extension member relative to the second extension member the movement configured to produce at least some expansion of the target inter-spinous space, (ii) a guide channel formed at least in part by a bore configured to extend from a proximal opening to distal opening in between the first and second extension members, and (ii) an orthopedic implant configured to be advanced at least partially through the guide channel and be positioned within the target inter-spinous space. The first and second extension members are removed from the target inter-spinous space, yet the orthopedic implant remains positioned within the inter-spinous space to maintain first and second vertebral bones of the spinal column separated by a desired distance.

In another embodiment, the assembly comprises: (i) an implant placement device comprising: at least a first extension member and a second extension member each of the first and second extension members comprising an elongated segment configured to extend from a proximal aspect to a distal aspect and each of the first and second extension members configured to be positioned within the target inter-spinous space at the distal aspect thereof, and a distraction mechanism configured to connect to the proximal aspect of each of the first and the second extension members, and to forcibly move the first extension member relative to the second extension member the movement configured to produce at least some expansion of the target inter-spinous space, the first and second extension members thereby creating a guide channel therebetween, (ii) an elongated member configured to be slidably positioned within the guide channel during advancement of the first and second extension members towards the target inter-spinous space, the elongated member being shaped to separate tissues ahead of the advancing first and second extension members, and (iii) an orthopedic implant configured to be advanced at least partially through the guide channel and be positioned within the target inter-spinous space. The elongated member is removed prior to advancement of the orthopedic implant through the guide channel. The first and second extension members are removed from the target inter-spinous space after the advancement of the orthopedic implant.

The implants and methods described permit treatment of spinal stenosis through a minimally invasive surgical procedure. Other features and advantages will be apparent from the following description of various embodiments, which illustrate, by way of example, the principles of the disclosed devices and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of an installer device that is adapted to position an implant in the inter-spinous space between two vertebras.

FIG. 2 shows the installer device in a distracted state.

FIG. 3 shows the installer device with an implant at the distal region of the installer arms.

FIG. 4 illustrates an exemplary implant placed within the inter-spinous space.

FIGS. 5A and 5B show perspective and cross-sectional views of an implant, respectively.

FIGS. 6A and 6B show another embodiment of an installer device without and with an exemplary imp/ant, respectively.

FIGS. 7 A and 7B show prospective and cross-sectional views of an exemplary implant in the un-deployed state.

FIGS. 8A and 8B show prospective and cross-sectional views of an exemplary implant in the deployed state.

FIG. 9A shows another embodiment of an installer device and an implant delivery instrument.

FIG. 9B shows perspective views of an implant delivery instrument.

FIG. 10 shows the delivery instrument after actuation such that an implant has rotated to a deployment position.

FIG. 11 shows the linkage mechanism of the implant delivery instrument.

FIG. 12 shows the delivery instrument coupled to the installer device prior to deployment of the implant.

FIG. 13 shows the implant in the inter-spinous space after deployment with the delivery instrument removed.

FIG. 14A shows another embodiment of an implant.

FIG. 14B shows an alternative application of the implant.

FIG. 15 shows an implant positioned in a inter-spinous space with a fixation screw anchoring the implant in place.

FIGS. 16 and 17 show perspective views of a device that is configured for placement between the spinous processes of two adjacent vertebras.

FIGS. 18 and 19 show exploded views of the device.

FIG. 20 shows a side, cross-sectional view of the device mounted to a pair of vertebrae.

FIG. 21 shows a side, cross-sectional view of the device mounted to a pair of vertebrae.

FIG. 22 shows perspective views of another embodiment in the disassembled state.

FIG. 23 shows additional views of the assembled implant of FIG. 22.

FIG. 24 shows the implant of FIG. 22 mounted on the sacrum.

FIG. 25 illustrates an oblique view of the mounted implant of FIG. 24.

FIG. 26 shows an additional embodiment.

FIGS. 27A and B show the implant of FIG. 26 placed into the spinal column.

FIG. 28A shows an additional embodiment of an orthopedic implant.

FIG. 28B shows an additional embodiment of an orthopedic implant.

FIG. 29A shows a lateral view of the vertebral bodies while FIG. 29B shows the implant in place.

FIGS. 30A and 30B show an additional embodiment of an implant.

FIG. 31 shows perspective views of the implant.

FIG. 32 shows the implant of FIG. 31 placed into the spinal column.

DETAILED DESCRIPTION

FIG. 1 shows a perspective view of an installer device 1605 that is adapted to position an orthopedic implant in the inter-spinous space between the spinous processes of two adjacent vertebras. For clarity of illustration, the vertebral bodies are represented schematically and those skilled in the art will appreciate that actual vertebral bodies include anatomical details not shown in FIG. 1. The device 1605 includes a platform 1610 having an actuator 1615 that can be used to separate a pair of distraction arms 1620 a and 1620 b. The platform member 1610 may include a scale for measuring the distraction distance or the distraction force. The scale can display the measured distance in a recognized physical unit or as an arbitrary designation (such as, for example, A, B, C, etc.) that is used for implant selection.

Each distraction arm 1620 has a semi-circular inner surface so that, in the non-distracted state, the arms 1620 collectively form an interior circular conduit. A curvilinear trocar with sharpened distal end 1625 b and discoid proximal member 1625 a is positioned through the circular conduit formed by arms 1620. Discoid proximal member 1625 a has locking tabs on its inferior surface that interact with complimentary tabs 1622 of arms 1620 and lock the trocar to the distraction arms. The sharpened end 1625 b emerges from the distal end of arms 1620 and, at the time of device insertion, end 1625 b divides the skin and soft tissue ahead of advancing arms 1620. Preferably, the distraction arms 1620 are positioned into the inter-spinous space at the stenotic spinal level under x-ray guidance. The trocar is removed and actuator 1615 is rotated to separate the distraction arms and apply a distraction force upon the spinous processes of the two adjacent vertebras.

FIG. 2 shows the device 1605 in a distracted state. With rotation of actuator 1615, each distraction arm 1620 is forcibly driven into the spinous process of the adjacent vertebral bone producing distraction of the inter-spinous space. In an embodiment, arms 1620 are curved, although the arms can be also straight or partially curved. A pathway is formed between the separated arms 1620 through which an implant can be driven into the inter-spinous space. The size of the needed implant is given by reading the scale along platform member 1610. FIG. 3 shows the device 1605 with an exemplary implant 1805 positioned at the distal region of the arms 1620. The implant 1805 is inserted into the proximal aspect of the pathway and advanced distally until it rests within the inter-spinous space. The implant is held in place by a placement handle (not shown) and the distraction arms and platform are then removed. Finally, the implant is distracted by actuating the placement handle. The implant is shown in FIG. 4 resting within the inter-spinous space.

FIGS. 5A and 5B illustrate perspective and cross-sectional views, respectively, of the implant 1805. The implant 1805 includes a first piece 1905 and a second piece 1910 that are movably attached to one another. A pair of wedge-shaped bearing members 1915 form a bearing surface between the two pieces 1905 and 1910. In addition, the pieces 1905 have respective shoulders 1925 that abut one another to guide and limit relative movement there between. The bearing members 1915 and the shoulders 1925 guide movement between the two pieces 1905 and 1910 such that the pieces can move and increase the dimensions of the implant 1805. The implant can be initially delivered into the inter-spinous space in a state of reduces size and then transitioned to the state of enlarged size after it is positioned within the inter-spinous space.

FIGS. 6A and 6B show another embodiment of an installer device 2105. The device 2105 includes a platform 2110 having an actuator 2115 that can be used to separate a pair of distractor arms 2120. In this embodiment, the distractor arms are straight. As discussed below, the arms 2110 can be used as a guide for positioning an implant 2205 into the inter-spinous space (FIG. 6B) FIGS. 7A and 78 show perspective and cross-sectional views of an exemplary implant 2205 in the un-deployed state. Implant 2205 contains at least longitudinal tract 2207 that interacts with the inner aspect of arms 2210. The implant 2205 includes first and second members 2210 and 2215 that are movably attached. When the members 2210 and 2215 are moved toward one another, one or more pivotably mounted arias 2220 are moved to a position that extends outwardly from the implant 2205. The arms can be moved to the extended position after implantation in the inter-spinous space.

FIGS. 8A and 8B show perspective and cross-sectional views of an exemplary implant 2205 in the deployed state. Note that the distal arms 2220 have a bearing articulation with the deploying portion of member 2210 while the proximal arms 2220 have a deformable base that is integrally attached to member 2210. Either mechanism may be employed on any of mounted arms 2220.

FIG. 9A illustrates an additional embodiment. A distraction platform with straight distraction arms is percutaneously positioned under x-ray guidance. The arms are placed lateral to the inter-spinous space. A delivery instrument 2303 is attached to the implant and used to place the implant into the inter-spinous space. FIG. 9B shows perspective views of the delivery instrument 2302. In the illustrated embodiment, the instrument 2302 includes a two-piece handle having a first arm 2310 and a second arm 2320 that is movably mounted relative to the first arm 231 b in a pivot or trigger fashion. The first and second arms are ergonomically arranged such that an operator can grasp the arms using a single hand. For example, the first arm 2310 is sized and shaped to support an operator's palm and thumb such as on a thumb grip 2322. Likewise, the second arm 320 can be grasped by the operator's fingers to pull the second arm 2320 toward the first au u 2310 and actuate the instrument 2302. A biasing member 2325 is interposed between the first and second arms. It should be appreciated that the instrument can be actuated with other mechanisms and need not use a two-piece handle configuration.

With reference still to FIG. 9B, a housing 2311 extends outward from the handle. The housing 2311 is sized and shaped to contain the implant 2205. In the illustrated embodiment, the housing 2311 has an elongated, tube-like shape and is partially hollow so as to contain the implant 2205 as well as an internal actuation mechanism that expels the implant from the housing. A slot 2330 is located at or near a distal end of the housing 2311. The slot communicates with an internal cavity in the housing 2311 in which the implant 2205 resides. The slot is sufficiently long and wide such that the implant 2205 can pass through the slot during deployment of the implant. FIG. 10 illustrates the internal mechanism of the placement device. FIG. 11 shows the instrument 2302 after actuation such that the implant 2205 has rotated (as represented by the arrow R) to a deployment position.

FIG. 12 shows the delivery instrument 2302 coupled to the installer device 2105 prior to deployment of the implant 2205. The elongated housing 2311 is placed in between the distractor arms 2120 such that a distal end of the housing 2311 is lateral to the inter-spinous space between the vertebrae. The delivery instrument is then actuated to rotate the implant 2205 into the inter-spinous space. FIG. 13 shows the implant 2205 in the inter-spinous space after removal of delivery instrument 2302.

FIG. 14A shows another embodiment of an implant. In this embodiment, the implant comprises a curved pin or screw 2805 that is sized and shaped to be passed through the spinous process of a vertebrae. The screw 2805 has a curved contour that permits a portion of the screw to extend through the spinous process with a distal region of the screw extending through the inter-spinous space. A proximal end of the screw 2805 is positioned at the exterior of the spinous process. The distal end of the screw 2805 abuts a surface of the spinous process of the adjacent vertebra. The pin may be at least partially comprised of a bone graft or bone graft substitute so as to fuse with the spinous process in which it is embedded. The pin maybe embedded in a first spinous process and abut a second spinous process, as shown in FIG. 14A, or it may be alternatively embedded in the second spinous process and abut the first spinous process, as shown in FIG. 14B.

FIG. 15 shows an implant positioned in an inter-spinous space and affixed to the spine with a fixation screw 3010. The implant 3005 is positioned within the disc space such that outer surface of the implant abuts adjacent vertebrae. A fixation screw 3010 extends through the spinous process and into the implant 3005. The screw may be at least partially comprised of a bone graft or bone graft substitute so as to fuse with the spinous process in which it is embedded. If the interior aspect of implant 3005 is also at least partially comprised of a bone graft or bone graft substitute, then screw 3010 can fuse with both the spinous process and implant 3005. This provides a bone bridge between the implant 3005 and the spinous process without direct fusion of the implant onto the spinous process.

FIGS. 16 and 17 show perspective views of a device 105 that is configured for placement between the spinous processes of two adjacent vertebral bodies. The device 105 includes a spacer region or central region 110 that is sized and shaped to fit between the spinous processes of the two adjacent vertebral bodies. The device 105 further includes a pair of attachment members 115 that are adapted to attach and anchor onto the spinous process of at least one of the vertebral bodies. The central region 110 can have a variety of shapes and sizes for placement between the spinous processes. The attachment members 115 can also have various sizes and shapes for attachment to the spinous processes.

FIGS. 18 and 19 show exploded views of the device 105. The device 105 includes attachment members 115 that are adapted to attach and anchor onto the spinous process of at least one of the vertebral bodies. Each attachment member 115 has a pair of downwardly-extending aims 305 that are sized to receive a spinous process therebetween. An upper portion of the attachment member 115 is sized and shaped to sit over the spinous process. The upper portion has a borehole that is sized to receive a threaded screw 410 during implantation: A locking mechanism 415 can be within the attachment, member 115 to serves to prevent unwanted movement and/or back out of the screw 410. While illustrated as a locking cam, the locking mechanism 415 may include any locking mechanism known in the art.

A first bearing member 425 has a rounded articulating surface that is adapted to interact with a complimentary articulating surface on a second bearing member 430. The member 425 is sized and shaped to be received in a cavity inside the member 430 so as to permit at least some rotational movement therebetween. A third bearing member 440 is at least partially dome-shaped and is adapted to couple to the members 425 and 430. In particular, the member 440 mates with the member 430 such as through a threaded engagement.

With reference still to FIGS. 18 and 19, member 430 includes a protrusion 445 that is sized and shaped to mate with an indentation 450 in the member 425. In the assembled device, the interaction of protrusion 445 and indentation 450 serves to limit the amount of rotation and lateral flexion between the members 425 and 430.

FIG. 20 shows a side, cross-sectional views of the device mounted to a pair of vertebrae. The members 115 can be coupled to one another by mating the member 425 beneath the member 430 such that articulating surfaces abut one another and permit rotational movement therebetween. The member 440 is positioned below the member 430 and secured thereto such as in a threaded relationship. This retains the device in the assembled state.

FIG. 21 shows an enlarged, cross-sectional view of the device in the assembled state and mounted between vertebrae. The member 425 has a rounded surface 605. The surface 605 interacts with a complimentary rounded surface 610 on the member 430. A space 630 is formed when the member 440 is secured onto the member 430. The member 425 resides within the space 630 in the assembled device. The space 630 permits a certain amount of “play” between the articulation of members 430 and 425. In an embodiment, the space 630 contains a malleable member that keeps members 425 and 430 in a preferred, neutral position and acts to return these members to the neutral position when they move away from it.

In addition, the curvilinear surfaces 605 and 610 define a spherical path of motion that is centered at Point A (shown in FIG. 20). That is, the surfaces 605 and 610 can move relative to one another along a pathway that is curvilinear or spherical. Alternative motion paths that are non-spherical may be alternatively made. In specific, a configuration that is similar, but not identical, to a hyperbolic paraboloid may be incorporated within the articulating surface. Moreover, the interaction of the protrusion 445 and indentation 450 allows a variable degree of rotational movements of one vertebral body relative to the other. The extent of rotation and lateral flexion permitted is dependant on the degree of flexion of the vertebral bodies. That is, with the vertebral bodies in flexion, the extent of rotation and lateral flexion permitted by the device is greater that amount of 14 rotation and lateral flexion that is permitted when the vertebral bodies are in extension. This feature reproduces the natural motion characteristics between the vertebral bodies.

FIG. 22 illustrates perspective views of device 3305 in the disassembled state. FIG. 23 shows sectional views of the assembled device 3305. Threaded wall 3320 surrounds central cavity 3315 and contains multiple full thickness bore holes 3325. The distal aspect of wall 3320 contains interior threads 3340 that couple with complimentary threads 3520 of distal member 3510. The central cavity 3315 is adapted to house a bone graft or bone graft substitute and permit fusion between the bone graft within cavity 3315 and the vertebral bone surrounding the outer aspect of device 3305. After placement of bone graft material within cavity 3315, distal member 3510 is screwed onto device 3305. The fusion forms across bore holes 3325.

The proximal aspect of device 3305 contains hexagonal cut out 3360. Cut out 3360 is adapted to accept a hex screw driver and the latter is used to drive device 3305 into bone. The proximal aspect of device 3305 contains at least one flap 3605 that is movably attached to device 3305. When a force is applied to the proximal aspect of device 3305, flap 3605 transiently and reversibly moves towards the center line of the device. In this way, flap 3605 functions as a malleable member and imparts a spring-like quality to the proximal aspect of device 3305.

In use, the central cavity 3315 is filed with a bone graft and distal member 3510 is threaded onto device 3305. Once assembled, distal member 3510 is rigidly attached to 3305. Under x-ray guidance, the device is percutaneously driven into the base of the superior articulating surface of the lower vertebral body and abuts the inferior surface of the inferior articulating surface of the superior vertebra. Preferably, a single device is used on each side of the vertebral midline, so that two devices 3305 are used at each stenotic level. The devices are shown attached to bone in FIGS. 24 and 25. As illustrated, each device 3305 limits the downward travel of the inferior articulating surface of the superior vertebra and limits the degree of extension at that spinal level. With time the bone contained within cavity 3315 will fuse with the adjacent bone and rigidly anchor the device to the vertebra. Because of the fusion the device does not to be anchored into the pedicle portion of the vertebra and it can be short in length.

FIG. 26 illustrates device 3705. The device is intended to reside within the facet joint and be anchored onto one, but not both, of the adjacent vertebras. The device may be affixed onto the vertebral bone using pins and a bone screw or the device may be at least partially comprised of a bone graft or bone graft substitute so as to fuse onto the adjacent bone. The device may be coated/made with osteo-conductive (such as deminerized bone matrix, hydroxyapatite, and the like) and/or osteo-inductive (such as Transforming Growth Factor “TGF-B,” Platelet-Derived Growth Factor “PDGF,” BoneMorphogenic Protein “BMP,” and the like) bio-active materials that promote bone formation. Further, one or more surfaces may be made with a porous ingrowth surface (such as titanium wire mesh, plasma-sprayed titanium, tantalum, Porous CoCr, and the like), provided with a bioactive coating, made using tantalum, and/or helical rosette carbon nanotubes (or other carbon nanotube-based coating) in order to promote bone in-growth or establish a mineralized connection between the bone and the implant.

The device is shown anchored to bone in FIGS. 27A and 27B. It is intended to at least partially replace the function of a natural facet joint that been at least partially removed at surgery. It may alternatively be used within an intact but degenerated facet joint to reestablish a functional articulation. FIG. 28A shows an additional embodiment of an orthopedic implant 705 positioned on two vertebral bodies of the lumbar spine. The implant 705 is attached onto the superior articulating surface and lamina of the lower vertebra and functions to stop the downward movement of the inferior articulating surface of the upper vertebral body. In this way, the device stops the extension of the two vertebral bodies and keeps them in relative flexion. The device can include contains one or more bore holes through which one or more screws are passed and anchored onto the underlying bone. As shown, the inferior aspect of the lamia of the upper vertebra is preferably removed (laminotomy) to decompress the nerve elements prior to device placement.

FIG. 28B shows an additional embodiment of an orthopedic implant 805 positioned on two vertebral bodies of the lumbar spine. The implant 805 is attached onto the superior articulating surface and lamina of the lower vertebra and transverses the facet joint between the two vertebral bodies. The superior surface of the device abuts the inferior aspect of the pedicle of the upper vertebral body. The implant functions to stop the extension of the two vertebral bodies and keeps them in relative flexion. The implant 805 can contain one or more bore holes through which screws are passed and anchored onto the underlying bone. FIG. 29A shows a lateral view of the vertebral bodies and FIG. 29B shows the implant 805 in place. Note that implant placement will necessarily place the lower articulating surface of the upper vertebral body more posteriorly and at least partially realign an anterior spondylolisthesis.

FIGS. 30A and 30B show an additional embodiment of an implant 1305. In an embodiment, the implant 1305 is a “c” shaped implant. FIG. 31 shows perspective views of the implant 1305. The implant 1305 functions to separate the top of the superior articular surface of the inferior body from the inferior aspect of the pedicle of the upper vertebral body. The implant 1305 has a size and shape such that the opening of the “C” can be positioned over at least a portion of the vertebral body. In an embodiment, a separate attachment device is not used to attach the implant 1305 to bone. In another embodiment, the implant 1305 contain one or more bore holes through which screws are passed and anchored onto the underlying bone. FIG. 32 shows the implant 1305 positioned on the bone.

The disclosed devices or any of their components can be made of any biologically adaptable or compatible materials. Materials considered acceptable for biological implantation are well known and include, but are not limited to, stainless steel, titanium, tantalum, combination metallic alloys, various plastics, resins, ceramics, biologically absorbable materials and the like. Any components may be also coated/made with osteo-conductive (such as deminerized bone matrix, hydroxyapatite, and the like) and/or osteo-inductive (such as Transforming Growth Factor “TGF-B,” Platelet-Derived Growth Factor “PDGF,” Bone-Morphogenic Protein “BMP,” and the like) bio-active materials that promote bone formation. Further, any surface may be made with a porous ingrowth surface (such as titanium wire mesh, plasma-sprayed titanium, tantalum, porous CoCr, and the like), provided with a bioactive coating, made using tantalum, and/or helical rosette carbon nanotubes (or other carbon nanotube-based coating) in order to promote bone in-growth or establish a mineralized connection between the bone and the implant, and reduce the likelihood of implant loosening. Lastly, the system or any of its components can also be entirely or partially made of a shape memory material or other deformable material.

Although embodiments of various methods and devices are described herein in detail with reference to certain versions, it should be appreciated that other versions, embodiments, methods of use, and combinations thereof are also possible. Therefore the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein. 

What is claimed is: 1.-10. (canceled)
 11. An orthopedic device, comprising: a first member configured to attach onto at least one first vertebra and limit motion of said first vertebra relative to a second, adjacent vertebra; wherein said first member defines a substantially curvilinear motion pathway of said first vertebra having at least one center of rotation near a natural instantaneous axis of rotation between said first vertebra and said second vertebra; and wherein said first member is configured to provide limited relative motion between said first vertebra and said second vertebra such that said relative motion is greater in flexion than in extension.
 12. The device of claim 11, wherein said first member is configured to attach onto at least one spinous process of said first vertebra.
 13. An assembly for placement of an orthopedic implant within a target inter-spinous space of a spinal column, said assembly comprising: an implant placement device comprising: at least a first extension member and a second extension member, each of said first and second extension members comprising an elongated segment configured to extend from a proximal aspect to a distal aspect, and each of said first and second extension members configured to be positioned within said target inter-spinous space at said distal aspect thereof; and a distraction mechanism configured to connect to said proximal aspect of each of said first and said second extension members, and to forcibly move said first extension member relative to said second extension member, said movement configured to produce at least some expansion of said target inter-spinous space; a guide channel formed at least in part by a bore configured to extend from a proximal opening to distal opening in between said first and second extension members; and an orthopedic implant configured to be advanced at least partially through said guide channel and be positioned within said target inter-spinous space; wherein said first and second extension members are removed from said target inter-spinous space, yet said orthopedic implant remains positioned within said inter-spinous space to maintain first and second vertebral bones of said spinal column separated by a desired distance.
 14. The assembly of claim 13, wherein a surface of said first extension member is configured to form at least a portion of said guide channel used for orthopedic implant placement.
 15. The assembly of claim 13, wherein a surface of said second extension member is configured to form at least a portion of said guide channel used for orthopedic implant placement.
 16. The assembly of claim 13, wherein said first extension member extends away from said distraction mechanism along a curvilinear trajectory.
 17. The assembly of claim 13, wherein said second extension member extends away from said distraction mechanism along a curvilinear trajectory.
 18. The assembly of claim 13, wherein said guide channel extends from a proximal end to a distal end along a curvilinear trajectory.
 19. The assembly of claim 13, further comprising an elongated member configured to be slidably positioned within said guide channel during advancement of said first and second extension members towards said target inter-spinous space, said elongated member being shaped to separate tissues ahead of said advancing first and second extension members.
 20. The assembly of claim 19, wherein said elongated member is configured to be removed from between said first and second extension members prior to advancement of said orthopedic implant through said guide channel.
 21. The assembly of claim 13, wherein said orthopedic implant comprises at least two segments configured to be movable relative to one another.
 22. The assembly of claim 13, wherein said orthopedic implant is adapted to transition from a first size to a second, larger size after advancement into said target inter-spinous space.
 23. An assembly for placement or an orthopedic implant within a target inter-spinous space of a spinal column, said assembly comprising: an implant placement device comprising: at least a first extension member and a second extension member each of said first and second extension members comprising an elongated segment configured to extend from a proximal aspect to a distal aspect and each of said first and second extension members configured to be positioned within said target inter-spinous space at said distal aspect thereof; and a distraction mechanism configured to connect to said proximal aspect of each of said first and said second extension members, and to forcibly move said first extension member relative to said second extension member said movement configured to produce at least some expansion of said target inter-spinous space, said first and second extension members thereby creating a guide channel therebetween; an elongated member configured to be slidably positioned within said guide channel during advancement of said first and second extension members towards said target inter-spinous space, said elongated member being shaped to separate tissues ahead of said advancing first and second extension members; and an orthopedic implant configured to be advanced at least partially through said guide channel and be positioned within said target inter-spinous space; wherein said elongated member is configured to be removed prior to advancement of said orthopedic implant through said guide channel; and wherein said first and second extension members are configured to be removed from said target inter-spinous space after said advancement of said orthopedic implant.
 24. The assembly of claim 23, wherein said implant placement device further comprises an actuatable mechanism configured to couple to a proximal segment of each of said first and second extension members, and to reversibly change a distance between said first and second extension members and thus a size of said guide channel.
 25. The assembly of claim 24, wherein actuation of said actuatable mechanism produces at least some movement of a spinous process of a first vertebral bone relative to a spinous process of a second vertebral bone, said target inter-spinous space being located between said first and second vertebral bones.
 26. The assembly of claim 24, wherein said implant placement device further comprises an indicia of a value of a distraction force delivered to said first and second extension members by said actuatable mechanism.
 27. The assembly of claim 24, wherein said implant placement device further comprises an indicia of a distance between said first and second extension members.
 28. The assembly of claim 24, wherein said implant placement device further comprises an indicia of a size of an implant appropriate for placement into said target inter-spinous space.
 29. The assembly of claim 23, wherein said guide channel is formed at least in part by a surface of said first extension member or a surface of said second extension member.
 30. The assembly of claim 23, wherein said orthopedic implant further comprises at least two segments configured to move relative to one another.
 31. The assembly of claim 23, wherein said orthopedic implant is configured to expand in size after advancement into said target inter-spinous space. 